In the case of large, back-lighted signs which are displayed on the streets or in malls or in other public places, and which are designed to convey periodically changing messages, the viewing surface of the sign customarily comprises a plurality of elements of different colors which are periodically manipulated to assume a series of preselected positions forming different images. This requires a central system of electrical and/or mechanical devices interposed between the light source and the viewing surface for moving the elements according to a prearranged program. One of the problems in prior art signs of this type is that the elements of the control system cast shadows which are visible on the front surface of the sign, interfering with the message which they are attempting to deliver.
Accordingly, it is the primary object of the present invention to improve the appearance and clarity of back-lighted signs comprising a plurality of movable components, by substantially eliminating or drastically reducing the shadows cast on the working face of the sign by the driving elements of the movable sign components.
This and other objects are achieved in a sign system according to the present invention in which the displayed characters and graphics visible from the transparent or translucent front viewing surface are backlighted from a multipoint or diffused light source. This technique tends to reduce or eliminate shadows cast by the electrical or mechanical elements which are interposed behind the viewing surface to manipulate the sign components. This may be achieved by interposing a plate of diffusing material to divide the area between the light source and the front surface of the sign into two chambers.
The diffusion panel may be constructed either by dispersion of diffusion pigment and/or particles within a transparent panel, or by utilization of a transparent panel with a surface treatment which causes random refractive dispersion of the departing light. The objective of the diffusion panel is to evenly distribute light throughout the entire viewing surface of the device without substantial diminuation of its intensity.
The rear chamber, farthest from the viewing surface, contains all of the light sources, and all the opaque electronic and electromechanical or other driving elements which operate the multifaceted sign elements. The forward chamber between the diffusion plate and the viewing surface contains all the multifaceted elements which form the displayed character or graphics. Light emanating from the light source is thus diffused through the diffusion panel so that the components in the forward chamber, with the exception of the multifaceted sign elements, are thus obscured from the front surface of the sign, thereby preventing contamination of the display.
This is accomplished by making all of the components from transparent materials, or where transparency is impossible, maintaining a ratio between the width of background feature and its distance from the viewing surface which will allow the light which passes from the light source throughout the diffusing panel to completely obscure the background feature. A preferred ratio has been found to be a minimum of two times the projected width of the background feature. The light rays are diffused when passing through the diffusion panel which scatters the light so that an opaque object, such as an electronic component or structural member, cannot be seen from the viewing surface.
In one embodiment, the multifaceted sign elements comprise a plurality of display elements which are rotatably assembled in individual control yokes in a geometric array with solenoids operating mechanical driving means, so that the display elements are oriented by a keyboard or computer system to assume a series of preselected patterns.
The front panel in this embodiment is made from a transparent material which will allow unrestricted viewing of the changeable display elements, yet protect the components within the device from harmful atmospheric elements. The front panel has an opaque white grid network which fits precisely between the display elements. This grid will appear white to the viewer during daylight due to the reflected sunlight, and black at night due to blocking of the display's rear light source, allowing enhanced color continuity between display elements of the same color. Each display element is made of a translucent material which is the primary display color, and consists of two viewing surfaces, one of which is the primary display color, and the other of which is a contrasting color, which are fastened together in a triangular configuration by means of a yoke providing a pivot point journalled on the yoke control axle, and a cam surface which interfaces with a selection key which operates to determine which surface is to be displayed. The two display surfaces of the display element are disposed at an acute angle to each other which allows the display element to rotate freely about its axis requiring only a minimum retraction from the viewing surface, which is insufficient to create an objectionable shadow of the contrasting color on the primary display color. The displayed surfaces of the display element are pressed firmly against the inside face of the transparent viewing surface during the viewing cycle, allowing maximum clarity and resolution of the displayed message and graphics. The display elements are mounted on their respective control yokes in rows which can be configured in any orientation within the supporting board, i.e., vertically, horizontally, or diagonally.
A series of selection keys which take the form of combs are mounted in transverse relation to the rows of display elements in such a way as to allow the teeth of the comb selection key to interface with the cam surface of the respective display elements causing the element to rotate about its axis, thereby causing the proper display surface to be exposed to the viewing surface. Each of the selection keys is electromechanically moved from a first to a second position against a spring bias to select a desired viewing surface of a respective display element. A programmed chip within a computer control device or a manually operated keyboard encodes data to determine in which position the selection key should be to position individual display elements to form desired overall device displays.
After the selection keys have been positioned for all positions along a row of display elements, that row is electromechanically moved in such a manner as to interface all display element cam surfaces with their corresponding selection keys, thereby turning all display elements to display the appropriately colored surface.
The device of this embodiment may be of modular construction, with series of modules interfaces with one another under computer control or keyboard control to form an integrated display, thereby minimizing size constraints on the overall display. Modules may be interfaced either by hard wiring, or with a series of electrical connectors.
A sign in accordance with the present invention may be formed, in one embodiment, of a mosaic of a plurality of identical square sign blocks fitted together against a framework formed of a row of lamp housings stacked together with projecting flanges which engage and support the blocks in contiguous relationship.
Electronic switching circuits may be located within each modular section of the sign, at a central location within the aggregate of modules, or at a convenient distant locations. Impulses from a centralized control circuit or computer will encode the switching circuits to activate the electromechanical features of the sign modules under a timing sequence which causes the module to display a desired message, or portion of a message, or graphic representation.
Input to the device, in the form of changes in graphics are accomplished either by direct entry through a computer keyboard or are encoded from copy into the control circuit or computer through an external encoding scanning device which may be of any of the types commercially available. Communication between the input computer or control circuit and the sign is accomplished either by hard wiring, telephone modem, or radio transmission.
Another embodiment of the invention, which may be appropriate for use, for example, for displaying the prices per gallon at gas stations, includes a rectangular box having a rear compartment which houses the light source, and a forward compartment which has a front viewing face of flat translucent plastic. As in the earlier embodiment, the front and rear compartments are separated by a light diffusing panel. Two parts make up the front face of the sign, which has a background of translucent plastic, on one part of which are certain permanently inscribed legends, which are depicted in the usual manner by painting them on or molding them into the viewing surface, and on another part of which are displayed the letters, figures or other graphics, which are changed from time to time. In the example under description, the latter comprises a numerical display which is changed from time-to-time to reflect variations in gas prices.
For convenience in forming the numerical display, a selected portion of the translucent front face of the sign may be inscribed with a series of transparent figure "eights", each of which is formed of hexagonal segments to accommodate what is known in the trade as the "seven segment display", whereby different digits from 0-9 may be displayed by blocking out selected segments of the transparent figure eight. This is achieved by mounting a flat, hexagonal blocking plate to rotate from blocking to open position adjacent each of the segments of a transparent figure eight, thereby forming any desired numerical display, such as price per gallon of gas.
The rotatable blocking plates, together with solenoid-driven gears, are installed against a flat white plastic backing plate, which is interposed into the forward compartment of the sign box just behind the front viewing face, so that the position of the blocking elements is coordinated to block and unblock each of the transparent openings of the segmented transparent figure eights of the display.
The solenoid driven gears for the blocking plates may be electrically or electronically controlled from a conventional cash register or a computerized circuit connected by a radio transmitter to a remote phone receiver, which is connected through its jack to a computer for programming the sign.
The light-diffusing panel interposed vertically between the rear light source in the sign box and the compartment containing the electromechanical driving elements functions to diffuse the light from the source, so that the shadows which they cast are obscured from the front viewing plate. Thus, the clarity of the sign message, as viewed in this case by the purchase, is preserved, which is important in financial transactions.
These and other objects, features, and advantages will be apparent to those skilled in the art, upon a view of the specification hereinafter with reference to the drawings.